Mechanically robust and fireproof separator for safer lithium-ion batteries with enhanced thermal stability

Lithium-ion batteries (LIBs) have been widely used in daily life and industrial manufacture, which concurrently suffers from the high thermal runaway (TR) hazard. The separator is believed to play a crucial role in affecting the performance and safety of battery. However, the influence of novel separator on TR action of battery is rarely investigated. In this paper, the polyimide-based flame-retardant separator (TiO₂@PZS@PI) is prepared via electrospinning and hot amination. Compared with Celgard separator, the ion conductivity, electrolyte uptake, porosity of separator are increased by 2011.2 %, 1511.8 %, 659.5 %, while the self-extinction time is reduced by 92.1 %. In comparison to Celgard battery, the battery with TiO₂@PZS@PI separator shows a marked increase in the starting temperature of TR (∼70 °C) and obvious delay in time to peak TR temperature (∼561 min). Moreover, such separator holds the marked ability to inhibit the growth of lithium dendrites. These results signify that the flame-retardant separator effectively improves the battery safety. In addition, the using of TiO₂@PZS@PI separator not only improves the specific discharge capacity of battery, but also delays the capacity attenuation of battery. Of note, the internal resistance of battery equipped with TiO₂@PZS@PI separator is greatly reduced. This work could provide innovative insights into the design of fire-resistant and mechanically robust separator to enhance the performance and safety of LIBS.